The announcement at the begining of the evening, or upon first meeting a group of females, that one will "take one for the team" and attempt to hook up with the ugly girl in the group (there's one in every group), thereby increasing the chance that another member of your party will hook up with someone attractive. The grumumba call is the ultimate selfless act amongst good freinds - normally reserved for only the most desperate of situations.

Since Joey had been dumped by his fiancee the day before, Kevin made the gramumba call as they entered the club.